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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        new Promise(resolve => {
            resolve()
        })
            .then(() => {
                return Promise.resolve()
            })
            .then(() => {
                console.log(4)
            })

        new Promise(resolve => {
            resolve()
        })
            .then(() => {
                console.log(1)
            })
            .then(() => {
                console.log(2)
            })
            .then(() => {
                console.log(3)
            })
            .then(() => {
                console.log(5)
            })

        console.log('===================');
        // new Promise(resolve => {
        //     resolve()
        // })
        //     .then(() => Promise.resolve())
        //     .then(() => {
        //         console.log(4)
        //     })

        // new Promise(resolve => {
        //     resolve()
        // })
        //     .then(() => {
        //         console.log(1)
        //     })
        //     .then(() => {
        //         console.log(2)
        //     })
        //     .then(() => {
        //         console.log(3)
        //     })
        //     .then(() => {
        //         console.log(5)
        //     })
    </script>
</body>

</html>